Composite fluid storage materials may be combined with enclosures, such as conformable enclosures, to provide a composite fluid storage unit that is lightweight and composed primarily of active fluid storage material. Composite hydrogen storage materials are examples. The mass and volume of non-storage materials is very low, resulting in fluid storage densities approaching the limit of the bulk storage material itself. The composite fluid storage material may be a porous, elastic solid. Any fluid entering or leaving the storage unit must be transported through the solid. Therefore, as the density of the solid increases to pack more active material into the enclosure, the ability to transport fluid is decreased of composite fluid storage materials.
The composite fluid storage unit may be utilized with a fuel cell, for example. The fuel cell may demand a flowrate of fluid at a high enough level to generate the consistent power required for its intended purpose. This flowrate can often be quite high, depending on the application. Similarly, when attempting to achieve a fast refueling of the storage unit, the flowrate of fluid into the unit must also be high. The flowrate, heat transfer and homogeneity of the fluid into or out of the composite fluid storage material are severely limited by the low porosity of the material.